Union Springs member of Marcellus formation named in this report. Consists of alternating beds of black limestone and sooty shale overlying Onondaga limestone and underlying Cherry Valley limestone member of Marcellus from Unadilla Valley westward to Seneca Lake. Thickness is 17 ft at type section in Wood's quarry. At Marcellus it is 13 ft thick, at Oneida Creek above Stockbridge Falls, 25 ft, and on Flint Creek, near Phelps, 9 ft. It is not known west of Phelps, Ontario Co., NY.

Marcellus Formation will be "formally" raised to subgroup status within the Hamilton Group and be divided into a lower Union Springs Formation and an upper Mount Marion Formation (in eastern New York), and an upper Oatka Creek Formation (in central and western New York), in a publication by Ver Straeten and others (in prep). Union Springs Formation will incorporate three members across New York: the Bakoven Member (geographically extended across the State of New York), the Stony Hollow Member (restricted), and the Hurley Member (new). The Hurley underlies the Cherry Valley Member at the base of the laterally equivalent Mount Marion and Oatka Creek Formations. The Bakoven unconformably overlies the Seneca Member or, where absent, the Moorehouse Member of the Onondaga Formation.
["Subgroup" not recognized as a formal stratigraphic rank term (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). Considered informal and should not be capitalized.]